Hi,
Can multiple concurrent transactions be opened from same session, and
(2) how does one achieve the equivalient of java.sql.Statement.addBatch and
executeBatch in hibernate?

thank you.

| eg |

(1) Not possible and would be very wrong (2) Hibernate automatically uses JDBC batch operations if possible.

If i'm expecting my use case to be frequent small reads and very few writes by different threads (use of threadlocal pattern is not possible, rmi), how often should i open/close session, or would it make sense to have a session pool, with session's being cleared and every checkin/checkout?

thank you,

|eg|

Command must be a good way for this use case :

abstract class Command {


protected abstract Serializable doExecute(Serializable[] args);

final public Serializable execute(Serializable[] args){
Session s = getSession();
try{

Serializable result = doExecute(args);
//commit
return result;
}finally{
s.close();
}


}


}
Remote object implementation is trivial:

Serializable execute( Serializable cmdId, Serializable[] args)
throws RemoteExeption{

return COMMAND_MAP.getCommand(cmdId).execute(args)

}


Client can send command id or it can use dynamic Proxy to convert method to command id before to invoke remote method.

I never use RMI in practice, but I experimented on j2ee container and it looks like there are no problems with this command suff. The nice thing about commands is reusability, it can be reused with any protocol or messaging (single line adapter) and it reduces code duplication.

This is very similiar to what i have now. I just wasn't sure that session-per-request was the way to go, mostly because i don't know what the overhead is for opening/closing a session.

thank you for your response.

You can think about session as wrapper for JDBC connection or client socket, it must be trivial to understand things by this analogy.